River system

A river system is a number of rivers which consists of one main river, which drains into a lake or into the ocean, and all its tributaries. The source is where the water is coming from, for example, from spring water (waterfalls), mountains etc. The water consistently flows and dumps the water into the ocean after it reaches the end. The water always comes from high to low, emptying into the river, which is called the mouth of the river.